Ball bat having a segmented barrel

ABSTRACT

A ball bat includes a segmented or decoupled barrel, which reduces the axial stiffness and BBCOR of the barrel, while providing little or no increase in the bat&#39;s moment of inertia. Segmenting the barrel, alone or in combination with other performance-reducing features, may be used to lower the BBCOR (or other specified performance characteristic) of the ball bat below the performance limits of a given regulatory association or other governing body.

BACKGROUND

Baseball and softball governing bodies have imposed various performance limits on ball bats with the goal of regulating batted ball speeds. Each association generally independently develops various standards and methods to achieve a desired level of play. Bat designers typically comply with these performance standards by adjusting the performance, or bat-ball coefficient of restitution (“BBCOR”), of their bat barrels. Typical methods of controlling BBCOR include thickening the barrel wall of a hollow metal bat, or increasing the radial stiffness of a composite bat via the selection of specific materials and fiber angles.

A composite bat's radial stiffness and fiber orientations are limited, however, by a given material thickness. The barrel walls in composite bats, therefore, are also often thickened to provide additional stiffness, which in turn limits BBCOR and barrel performance.

Thickening a barrel wall generally increases the bat's weight and, more importantly, it's “swing weight” or moment of inertia (“MOI”). MOI is the product of: (a) a mass, and (b) the square of the distance between the center of the mass and the point from which the mass is pivoted. Mathematically, this is expressed as follows:

MOI=ΣMass×(Distance)²

Accordingly, the MOI dictates that it becomes increasingly difficult to swing a bat as the bat's mass increases or as the center of the bat's mass moves farther from the pivot point of the swing (i.e., farther from the batter's hands). Because thickening the barrel wall increases the bat's weight at a region relatively distal from the batter's hands, doing so also increases the bat's MOI. Thus, while thickening a barrel wall may effectively stiffen the barrel and reduce its performance, the consequent increase in MOI is generally undesirable for batters.

SUMMARY

A ball bat includes a segmented or decoupled barrel, which reduces the axial stiffness and BBCOR of the barrel, while providing little or no increase in the bat's moment of inertia. Other features and advantages will appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein the same reference number indicates the same element throughout the views:

FIG. 1 is a perspective view of a ball bat, according to one embodiment.

FIG. 2 is a side-sectional view of a ball bat including a segmented barrel, according to one embodiment.

FIG. 2A is a magnified view of Section A of FIG. 2.

FIG. 3 is a side-sectional view of a ball bat including a segmented barrel, according to another embodiment.

FIG. 3A is a magnified view of Section B of FIG. 3.

FIG. 4 is a side-sectional view of a ball bat including a segmented barrel, according to another embodiment.

FIG. 4A is a magnified view of Section C of FIG. 4.

DETAILED DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described. The following description provides specific details for a thorough understanding and enabling description of these embodiments. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, some well-known structures or functions may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments.

The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this detailed description section.

Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of items in the list.

Turning now in detail to the drawings, as shown in FIG. 1, a baseball or softball bat 10, hereinafter collectively referred to as a “ball bat” or “bat,” includes a handle 12, a barrel 14, and a tapered section 16 joining the handle 12 to the barrel 14. The free end of the handle 12 includes a knob 18 or similar structure. The barrel 14 is preferably closed off by a suitable cap 20 or plug. The interior of the bat 10 is preferably hollow, allowing the bat 10 to be relatively lightweight so that ball players may generate substantial bat speed when swinging the bat 10. The ball bat 10 may be a one-piece construction or may include two or more separate attached pieces (e.g., a separate handle and barrel), as described, for example, in U.S. Pat. No. 5,593,158, which is incorporated herein by reference.

The ball bat 10 is preferably constructed from one or more composite or metallic materials. Some examples of suitable composite materials include fiber-reinforced glass, graphite, boron, carbon, aramid, ceramic, Kevlar, or Astroquartz®. Aluminum or another suitable metallic material may also be used to construct the ball bat 10. A ball bat including a combination of metallic and composite materials may also be constructed. For example, a ball bat having a metal barrel and a composite handle, or a composite barrel and a metal handle, may be used in the embodiments described herein.

The ball bat 10 may have any suitable dimensions. The ball bat 10 may have an overall length of 20 to 40 inches, or 26 to 34 inches. The overall barrel diameter may be 2.0 to 3.0 inches, or 2.25 to 2.75 inches. Typical ball bats have diameters of 2.25, 2.625, or 2.75 inches. Bats having various combinations of these overall lengths and barrel diameters, or any other suitable dimensions, are contemplated herein. The specific preferred combination of bat dimensions is generally dictated by the user of the bat 10, and may vary greatly between users.

The ball striking area of the bat 10 typically extends throughout the length of the barrel 14, and may extend into the tapered section 16 of the bat 10. For ease of description, this striking area will generally be referred to as the “barrel” throughout the remainder of the description. Accordingly, the handle may be referred to as being connected to the barrel directly or indirectly via a tapered section.

A bat barrel 14 generally includes a maximum performance location or “sweet spot,” which is the impact location where the transfer of energy from the bat 10 to a ball is maximal, while the transfer of energy to a player's hands is minimal. The sweet spot is generally located at the intersection of the bat's center of percussion (COP) and its first three fundamental nodes of vibration. This location, which is typically about 4 to 8 inches from the free end of the barrel 14, does not move when the bat is vibrating in its first (or fundamental) bending mode.

The bat barrel 14 in the embodiments described herein preferably includes a radially outer wall that is segmented or decoupled in the axial direction such that longitudinally or axially neighboring barrel segments or rings are substantially or completely isolated from one another. The neighboring barrel segments may be spaced from one another by any suitable distance, for example, between approximately 0.02 to 0.06 inches, preferably approximately 0.04 inches. The spaces between the neighboring barrel segments are preferably filled with an adhesive material, such as an elastomeric adhesive of rubber, urethane, foam, Surlyn® or the like, such that the neighboring barrel segments are bonded to one another. The radially outer surfaces of the neighboring barrel segments, and the interspersed adhesive, are preferably flush with one another to provide a smooth, continuous hitting surface.

Segmenting the barrel in this manner reduces the axial stiffness of the barrel, which lowers the barrel's performance, surprisingly even when the barrel includes multiple walls. The barrel may be segmented into any suitable number of sections or rings to meet the performance requirements of a given regulatory association or other governing body. For example, a barrel may include four to six segments or rings.

As shown in FIGS. 2 and 2A, a ball bat includes a barrel having an outer barrel wall 30 and an inner barrel wall 32. The outer and inner walls are preferably bonded together with an elastomeric adhesive, such as one of those described above, or via another suitable bonding material. In one embodiment, the outer and inner walls are bonded together via a relatively thick elastomeric layer 34, as described, for example, in U.S. Pat. No. 6,663,517, which is incorporated herein be reference. The elastomeric layer 34 may, for example, have a thickness of approximately 0.02 to 0.06 inches, preferably approximately 0.04 inches.

Slices or cuts are made through the outer barrel wall 30 and preferably terminate at the elastomeric layer 34, resulting in an outer wall made up of multiple isolated barrel segments 36, 38, 40, 42, 44 or ring-like structures. The spaces between the neighboring barrel segments are preferably filled with an adhesive material 46, such as one of the elastomeric adhesives described above.

As shown in FIGS. 3 and 3A, in another embodiment, multiple multi-plane barrel segments, including radially external and internal portions, are adhered to one another to form a fully segmented barrel (i.e., both the inner and outer barrel walls are segmented). An internal initial barrel segment 50 preferably originates at or near, and merges or is otherwise integral with, the external tapered section 16 of the ball bat. An external portion 51 of a first multi-plane barrel segment 52 is adhered to the initial barrel segment 50 via a suitable adhesive 54, such as one of the elastomeric adhesives described above. Accordingly, the initial barrel segment 50 provides radial support for the external portion 51 of the first multi-plane barrel segment 52.

An internal portion 53 of the first multi-plane barrel segment 52, similarly, is adhered to an external portion 55 of a second multi-plane barrel segment 56 via another layer of adhesive 58, such that the internal portion 53 provides radial support for the external portion 55. Following this pattern, an internal portion 57 of the second multi-plane barrel segment 56 is adhered to an external portion 59 of the next successive multi-plane barrel segment 60 via another layer of adhesive 61. This pattern continues until an external final barrel segment 62, which engages or is secured to the cap 20 (or which could be used to form the cap itself) of the ball bat, is reached. The pattern could alternatively be reversed, such that the internal initial barrel segment is located at the cap-end of the barrel and the external final barrel segment is located adjacent to the tapered section of the ball bat.

As shown in FIGS. 4 and 4A, in another embodiment, the barrel includes a recessed section 70 in the hitting zone having a reduced diameter relative to the neighboring tapered section 16 of the ball bat. One end 71 of the recessed section 70 preferably merges or is integral with the tapered section 16. The radially outer surface of the recessed section 70 is preferably coated or covered with a layer of elastomeric adhesive 72 or another suitable bonding material. External barrel segments 74, 76, 78, 80, 82 or rings are adhered to the recessed section 70 via the elastomeric layer 72 (and are spaced apart from one another such that they are substantially or completed isolated from one another).

The spaces between the neighboring barrel segments are preferably filled with an adhesive material 84, such as one of the elastomeric adhesives described above, such that the neighboring barrel segments are bonded to one another. The cap-end 86 of the barrel preferably has an increased diameter relative to the recessed section 70 such that its radially outer surface is flush with the neighboring external barrel segment 82.

Assuming all other features are essentially equal (e.g., wall thickness, elastomeric adhesive used, and so forth), the performance and durability would generally vary between the bats of the above described embodiments. For example, the ball bat shown in FIGS. 2 and 2A would generally exhibit lower performance (i.e., lower BBCOR) and durability than would the ball bat shown in FIGS. 4 and 4A. This is largely due to the rigidity of the supporting frame provided by the integral recessed section 70 in the embodiment shown in FIGS. 4 and 4A.

As a result, players would generally experience more feedback, or vibrations, from this more rigid bat during a hit, particularly when contact occurs away from the sweet spot of the barrel. Such a ball bat may be desirable to more skilled players who want feedback to tell them how well they struck the ball. Lesser skilled players, conversely, generally tend to prefer the increased isolation between the inner barrel wall 32 and the handle 12 provided by the ball bat shown in FIGS. 2 and 2A, which lessens the sting felt during hits away from the sweet spot.

The fully segmented ball bat shown in FIGS. 3 and 3A, in which barrel segments overlap with neighboring barrel segments, generally provides the least amount of axial connectivity to the handle, i.e., the lowest axial stiffness, of the described embodiments. Accordingly, the ball bat of this embodiment generally exhibits the lowest performance, or BBCOR, of the described ball bats. The lack of rigidity and connectivity to the handle lowers the effective mass of the bat impacting the ball, i.e., the bat barrel at the point of impact is isolated from the rest of the bat due to the lack of axial stiffness. Accordingly, players will generally feel less feedback in this ball bat than in the other described embodiments.

The durability and performance of the ball bats described herein may be modified based on the elastomeric materials used in the bat barrel. As understood by those skilled in the art of bat design, properties such as damping, adhesion, and long-term durability of the ball bat may be affected by the choice of elastomeric material. Rubbers, for example, tend to exhibit relatively low damping characteristics but have relatively high densities and may not have sufficient tear strength to offer a highly flexible system. Also, adhesion to metal can be very high when using rubber if vulcanization is used to adhere components to one another.

Urethane provides higher damping than many rubbers and comes in a form that is generally easier to use in a variety of assembly processes. Silicone or foamed elastomers may be used, as well. Foamed elastomers, while generally lighter in weight, tend to have lower tear strength and exhibit higher damping than fuller-density elastomers. Foamed elastomers may work well in the ball bats shown in FIGS. 4 and 4A, for example, but, due to their lower tear strength, may not work as well in the more fully segmented ball bat shown in FIGS. 3 and 3A. Adding fibers strands to the elastomer could provide increased tear resistance, however.

In general, elastomeric materials having a lower coefficient of restitution (“COR”) will provide a ball bat with less rebound performance. Changing the durometer of the elastomeric material could also affect rebound performance, depending on the stiffness of the overall bat barrel and the hardness of the ball. In general, the lower the durometer of the elastomer, the higher the ball rebound performance, as long as the COR of the elastomer is not decreased. The COR of an elastomer, however, commonly decreases as its durometer decreases. Thus, a bat designer must take into consideration the properties of the specific elastomer being used.

Segmenting the barrel creates an extreme shift in the stiffness of the barrel. Indeed, the outer barrel wall (and optionally the inner barrel wall) is effectively decoupled from the handle of the bat. This lack of stiffness causes larger deflections and much lower frequency responses in the bat than in bats not having a segmented barrel. The dramatic decrease in bat frequency response decouples or mistimes the bat rebound response to the ball rebound response. This effect is similar to a trampoline that flexes back to shape after the jumper has left the canvas surface. By segmenting the barrel, the axial stiffness becomes low enough that the ball rebound is significantly reduced. The amount of ball rebound lost depends upon how slow the bat recovers. In general, decreasing the stiffness of a body lowers the frequency response of the body, i.e., a more flexible bat barrel is slower to respond.

A ball bat having a segmented barrel not only helps to control ball rebound performance, but also generally reduces sting experienced by players when a ball impacts the bat away from the sweet spot of the barrel. This is because the lack of axial stiffness limits the transmission of vibration energy down the length of the bat to the player's hands. Further, most elastomeric adhesives or other flexible adhesive materials typically are highly damped, which further reduces the sting felt when a ball strikes the barrel away from the sweet spot.

As discussed, axially segmenting the bat barrel generally reduces its durability. This can be compensated for by slightly increasing the thickness of the barrel walls, avoiding stress risers (e.g., sharp edges, corners, and so forth) in the bat design, or sufficiently supporting the inner barrel wall to prevent excessive deflection. In any of the described embodiments, for example, an additional, radially innermost barrel wall may be attached to or in engagement with a radially inner surface of the radially inner barrel wall to provide additional strength and durability to the ball bat. The additional wall could be made of a rigid material (e.g., aluminum, magnesium, titanium, or some fiber-reinforced plastic materials), or of a semi-rigid material (e.g., thermoplastic, some other fiber-reinforced plastic materials, or an additional layer of elastomeric material, which may optionally include reinforcing fibers). The inclusion of an additional barrel wall may be particularly useful in the fully segmented ball bat shown in FIGS. 3 and 3A.

It was initially expected that a segmented barrel would provide improved ball rebound performance. This expectation was generally based on the observation that double-wall bats are more flexible than single-wall bats. Similarly, bats including an elastomeric core are generally more flexible than single-wall bats. Thus, it was believed that making the bat even more flexible would improve barrel performance. This was not the case. In fact, it was found that a double-wall bat having a segmented barrel generally provides significantly lower rebound performance than does a typical, unsegmented single-wall ball bat made of similar materials and having similar dimensions. Accordingly, a segmented barrel may be utilized, alone or in combination with other performance-reducing features, to reduce a ball bat's BBCOR (or other specified performance characteristic) below the limits imposed by regulatory associations or governing bodies, while providing little or no increase in the bat's moment of inertia.

Any of the above-described embodiments may be used alone or in combination with one another. Furthermore, the ball bat having a segmented barrel may include additional features not described herein. While several embodiments have been shown and described, various changes and substitutions may of course be made, without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims and their equivalents. 

1. A ball bat including a handle connected to a barrel in an axial direction, with the barrel comprising: a radially inner wall; a layer of a first adhesive material on a radially outer surface of the radially inner wall; a plurality of circumferential, radially outer segments adhered to the radially inner wall via the first adhesive material, wherein the radially outer segments are spaced apart from one another in the axial direction; and a second adhesive material adhering the radially outer segments to one another in the axial direction.
 2. The ball bat of claim 1 wherein radially outer surfaces of the radially outer segments are flush with one another.
 3. The ball bat of claim 1 wherein the ball bat includes a tapered section between the barrel and the handle in the axial direction, and wherein the radially inner wall is not in contact with the tapered section or the handle of the ball bat.
 4. The ball bat of claim 1 wherein the ball bat includes a tapered section between the barrel and the handle in the axial direction, and wherein one end of the radially inner wall is integral with the tapered section, while a substantial portion of the radially inner wall is recessed relative to the tapered section.
 5. The ball bat of claim 1 wherein the radially outer segments are spaced apart from one another in the axial direction by approximately 0.02 to 0.06 inches.
 6. The ball bat of claim 1 wherein the layer of the first adhesive material has a thickness of approximately 0.02 to 0.06 inches.
 7. The ball bat of claim 1 wherein the first and second adhesive materials comprise the same material.
 8. The ball bat of claim 1 wherein the first and second adhesive materials comprise elastomeric adhesive materials.
 9. The ball bat of claim 1 wherein the barrel includes four to six radially outer segments.
 10. The ball bat of claim 1 further comprising a radially innermost wall attached to or in engagement with a radially inner surface of the radially inner wall.
 11. A ball bat including a handle connected to a barrel in an axial direction, with the barrel comprising: a radially inner initial segment; a first multi-plane segment including a radially outer portion adhered to a radially outer surface of the initial segment, and a radially inner portion axially adjacent to the initial segment; at least one additional multi-plane segment, wherein each additional multi-plane segment includes a radially outer portion adhered to a radially outer surface of a radially inner portion of a previous multi-plane segment, and a radially inner portion axially adjacent to the radially inner portion of the previous multi-plane segment; and a radially outer segment adhered to a radially inner portion of the last of the additional multi-plane segments.
 12. The ball bat of claim 11 wherein the ball bat includes a tapered section between the barrel and the handle in the axial direction, and wherein the initial segment is integral with the tapered section.
 13. The ball bat of claim 11 wherein the radially outer segment is connected to or integral with a cap at a free end of the barrel.
 14. The ball bat of claim 11 wherein an elastomeric adhesive material is used to adhere the segments to one another.
 15. The ball bat of claim 14 wherein the elastomeric adhesive material has a thickness of approximately 0.02 to 0.06 inches.
 16. The ball bat of claim 11 wherein the radially outer portions of the multi-plane segments and the radially outer segment are spaced apart from one another in the axial direction by approximately 0.02 to 0.06 inches.
 17. The ball bat of claim 11 wherein the radially outer portions of the multi-plane segments and the radially outer segment have radially outer surfaces that are flush with one another.
 18. The ball of claim 11 wherein the barrel includes three multi-plane segments.
 19. The ball bat of claim 11 further comprising a radially innermost wall attached to or in engagement with at least one of the radially inner segment and the radially inner portions of the multi-plane segments.
 20. A ball bat including a handle connected to a barrel in an axial direction, with the barrel comprising: a plurality of radially outer rings spaced apart from, and adhered to, one another in the axial direction, wherein radially outer surfaces of the radially outer rings provide an external hitting surface; and a radially inner wall adhered to the plurality of radially outer rings. 